Fluid compressor



Dec. 19, 1967 N. J. GAWIN 3,358,908

FLUID COMPRESSOR Filed Oct. 22, 1965 INVENTOR /YORBERT J GAWIN United States Patent Ofifice 3,358,9h8 Patented Dec. 19, 1967 AESTRACT OF THE DISCLOSURE A diaphragm type air compressor is provided with a head unit including a pumping chamber with an air inlet opening to the atmosphere and an outlet chamber connected to an air storage tank and by outlet opening to the pumping chamber. A leaf spring valve is connected within the pumping chamber and overlies the inlet opening. A similar leaf spring is secured within the outlet chamber overlying the outlet opening. A small leak port or orifice extends between the outlet chamber and the pumping chamber. The orifice includes a relatively large diameter portion immediately adjacent the outer end of the inlet valve leaf spring and a small diameter portion terminating Within the outlet chamber. The inlet leaf spring is crowned outwardly at the inlet opening. When the compressor is turned off the compression chamber is relieved by the crowned spring such that it will pop open and exhaust the system through the leak port. In operation, the leak port is open during the suction stroke but is held closed during the compression stroke.

This invention relates to a fluid compressor and particularly to a means for unloading of the compressor system during the off cycle of the compressor. In air compressor and similar devices, the output of the compressor is supplied directly to the system or through a compressed air storage means. Certain applications require pressure relieving or unloading means which may control the output pressure and relieve the pressure from the compression chamber during the off cycle of the compressor. System unloading has been found to be particularly desirable in rapid cycling machines operated with the use of compressed air.

Various solenoid control valve systems have been suggested in connection with compressors to provide a system leak. The solenoid systems add additional parts and maintenance to the system.

A compressor unit having a simplified unloading means is also shown in U.S. Patent 2,536,995 wherein the compressor chamber proper is unloaded during the off cycle by the use of a convex leaf spring inlet valve. When the compressor is turned off, the convexity of the valve provides communication between the compression chamber and the atmosphere. This system however only relieves the compressor and not the total system.

A very simple arrangement employs a direct leak from the high compression side of the compressor to the atmosphere or inlet side of the compressor pump. For example, the Buschmann Patent 2,520,674 discloses the use of a small passageway connected between the inlet and the outlet chambers of a compressor to provide a continuous leak or bleed from the high pressure chamber to the atmosphere. Although such a system is simple and therefore highly desirable, it noticeably increases the capacity requirements of the compressor to supply the load and the leak.

The present invention is particularly directed to an improved unloading system having the simplicity of a direct leak port in combination with means to substantially reduce the loss occasioned by such direct leak and thereby reduces the increased capacity requirement of the compressor.

Generally, in accordance with the present invention, a leak passageway or port is inserted between a high pressure chamber and the compression chamber with the leak port opened and closed by a suction valve member which preferably is an integral part of the inlet valve structure which also includes means to unload the compressor. The leak port is therefore effective only on the suction stroke while the compressor is running. On the compression stroke, the inlet port and the leak port are closed. This will reduce the system leak to fifty percent of the running time of the compressor and thereby substantially minimize the losses and the necessary increase in capacity of the compressor for any given load while providing a simple bleed or unloading of the compressor during the down time.

In accordance with a preferred construction of the present invention, the inlet port is provided in the head unit of a diaphragm type compressor with a leaf spring valve overlying the inlet port. The leaf spring valve is preferably crowned outwardly of the inlet port for relieving the pressure within the compression chamber during the off: cycle of the compressor. The leak port is located between the free or outer end of the leaf spring and the high pressure chamber. The area of the inlet port is substantially larger than the area of the leak port and consequently a small differential at the inlet port causes closure of both ports during the compression stroke. When the compressor is turned off, the compression chamber is relieved by the crowned inlet valve. When the pressure reduces to a selected degree, the valve pops open and exhausts the system through the leak port.

Further, the leak port preferably includes a small orifice portion extending from the high pressure chamber and terminating in an enlarged portion immediately adjacent the inlet valve. The larger portion immediately adjacent the leaf spring plate determines the relative pressure differentials required to open and close the valve structures at the respective ports. The smaller orifice determines the rate of flow of the air from the high pressure system when the leak port is uncovered.

The present invention provides a simple and reliable means for bleeding or unloading of the compressor and the system pressure while minimizing and reducing losses occasioned by a direct leak structure.

The drawing furnished herewith illustrates a preferred embodiment of the present invention in which the above advantages and features are clearly described and shown as well as others which will be clear from the following description of the drawings.

In the drawing:

FIG. 1 is generally a sectional view of a compressor incorporating a controlled leak port constructed in accordance with the present invention;

FIG. 2 is an enlarged view of a portion of FIG. 1 more clearly showing the leak port structure and loca-- tion of the present invention; and

FIG. 3 is a fragmentary bottom view taken generally on line 3-3 of FIG. 1.

Referring to the drawing and particularly to FIG. 1, the embodiment of the invention is shown in connection with an air pump 1 connected to be driven by an electric motor 2 generally as shown in the previously referred to Hadley Patent 2,536,995. The motor 2 may be of any suitable variety such as a small alternating current motor or the like and no further description of the motor is given.

The pump 1 is a diaphragm type pump similar to that shown in the above patent and includes a mounting frame 3 secured to form one end of the motor 2 and having a pump cylinder 4 projecting laterally and outwardly of the motor 2. A piston 5 is connected to an extended end of motor shaft 6 in any suitable manner for reciprocation 3 within the cylinder 4. A diaphragm '7 is secured to the outer face of the piston 5 by a retainer 8 and extends radially outwardly therefrom. The outer periphery of diaphragm 7 is clamped in sealing engagement between the outer end of the cylinder 4 and a cylinder head 9 which is bolted to the outer end of the cylinder 4. The head 9 generally includes an inverted cup-shaped body 10 closed on the inner end by a valve plate 11 to define a compression chamber 12 between the diaphragm 7 and the valve plate 11. A central inlet opening or port 13 extends through the head 9 and valve plate 11 and terminates in communication with the compression chamber 12. A screened breather assembly 14 covers the outer end of the inlet port 13 to filter air moving into the compression chamber 12. The opposite or inner end of the inlet port 13 is closed by a crowned inlet valve member 15 secured to plate 11 to one side of the port. An exhaust port 16 is provided within the plate 11 to the one side of the inlet port 13 to provide communication between the compression chamber 12 and an annular high pressure chamber 17 in the head body 10. A similar leaf spring valve member 18 overlies the outlet port 16 within the high pressure chamber 17 A discharge port 19 interconnects the high pressure chamber 17 to a suitable outlet conduit 20 for transfer of the air directly to the compressed air load.

The structure of FIG. 1 described above generally is similar to that heretofore employed as shown in the Hadley patent and briefly functions as follows.

During the suction stroke when the diaphragm 7 moves inwardly, the valve member 15 is drawn inwardly from the port 13 and draws air in through the inlet opening. The same pressure exerted through the outlet port 16 and the high pressure in chamber 17 forces valve member 18 to tightly close the port 16 and prevent flow from the high pressure chamber into the compression chamber. During the compression stroke when the diaphragm 7 moves outwardly, the air is compressed and closes the inlet valve member 15 over the inlet port 13 and at a selected pressure overcomes the pressure in chamber 17 acting on the outlet valve member 18 to open the outlet port 16 and transfer the air into the chamber 17 In accordance with the present invention, a leak port 21 is provided extending between the high pressure chamber 17 and the free end of the inlet valve member 15. Consequently, in the operation of the compressor as noted above, during the suction stroke, the member 15 opens the leak port 21 to bleed the high pressure chamber. During the compression stroke, however, the member 15 covers both the inlet port 13 and the leak port 21 to prevent loss of air from the system. Consequently, the present invention provides a leak port which is automatically effective during about fifty percent of the operating cycle without undue complication in the arrangement and construction of the compressor. Further, when the compressor stops, the compression chamber 12 is relieved as a result of the crowned inlet valve member 15. At a selected compression chamber pressure, the high pressure in chamber 17 pops the valve member 18 outwardly to uncover the leak port 21 and the inlet port 13 to bleed the compression chamber 12 and the high pressure chamber 17 to atmospheric pressure.

More particularly, in the illustrated embodiment of the invention, the head 9 includes the inverted cup-shaped body 10 with a centrally located annular wall 22 defining the inlet port 13 and the high pressure chamber 17 as an annular chamber encircling the inlet port. The valve plate 11 is secured in sealed relationship abutting the lower surface of the valve head body 10 and wall 22 by a plurality of bolts 23 threaded into appropriate portions of the body and the inner annular wall. A gasket 24 is disposed between the mating faces of the valve plate 11 and the valve head 9 to provide a fluid tight seal therebetween.

The inlet valve member 15 is a thin flexible rectangular spring metal member of a width slightly greater than the width of the inlet port 13. One end of the valve member 15 is secured by a pair of small mounting bolts 25 to plate 11. The bolts 25 pass through the member 15 and thread into suitably tapped openings in the valve plate 11. The member 15 extends from the bolts 25 over the inlet port 13 and the leak port 21. The illustrated valve member 15 is provided with a convex or crowned portion 26 in alignment with the inlet port 13 such as shown substantially enlarged in FIG. 2. In the normal standby position, the valve member 15 provides a direct communication between the inlet port 13 and the compression chamber 12. The leak port 21 however is covered by the outermost and fiat end 27 of the valve member 15.

The outlet port 16 is radially spaced from the inlet port 13 in the valve plate 11. The valve member 17 is a thin flexible rectangular spring metal member secured to the outer face of valve plate 11 by rivet 28. Member 17 acts as a leaf spring to selectively open and close the outlet port 16 in response to reciprocation of the diaphragm 7. A valve stop, not shown, may be secured to the face of the valve plate 11 to limit the outward movement of the free end of the member 17.

The illustrated leak port 21 which particularly forms the subject matter of the present invention is generally disposed diametrically opposite from the fulcrum position of the valve member 15 as defined by the securing bolts 25. The leak port 21 includes a small orifice portion 29 extending from the outer face of the valve plate 11 which defines the one wall of the high pressure chamber 17. The orifice portion 29 extends angularly toward the outer or free end 27 of the inlet valve member 15 and terminates in an enlarged leak port portion 30 aligned with the outer end 27 of the inlet valve member 15.

In operation, the inward movement of the diaphragm 7 creates a suction force on the discharge valve member 18 to close the outlet port 16 and on the inlet valve member 15 to open the inlet port 13 and the leak port 21. Air is drawn into the compressor and the high pressure chamber 17 and the connected load system bleeds down for the period the member 15 is open. On the reverse or the compression stroke, the inlet valve member 15 is forced outwardly to simultaneously and tightly seal the inlet port 13 and the leak port 21. Normally, the substantially greater area of the inlet port 13 with respect to the enlarged portion 30 of the leak port 21 is such that a relatively small differential across the member 15 at the inlet port 13 is sufficient to overcome the opening force of the pressure in chamber 17 acting across the outer end of the member such that during the compression stroke both of the ports are securely closed and on the suction stroke both are opened.

The effect of the pressure differentials at the respective ports 13 and 21 are dependent not only on the relative areas but the difference in the fulcrum lengths of member 15. In an actual unit constructed in accordance with the present invention, the arrangement was constructed such that a differential pressure in excess of 15 pounds per square inch (psi) was required at the bleed port 21 to open the inlet valve member 15 against a one-half pound per square inch differential at the inlet port 13.

When the compressor stops, the crowned inlet valve member 15 unloads or bleeds the cylinder pressure to permit rapid starting of the compressor. When the cylinder pressure reduces to the minimum holding pressure across the inlet port 13, the valve member 15 pops to the open position to exhaust the high pressure chamber and the load system.

The small orifice portion 29 regulates the rate of flow or the bleed rate while the relative areas of the enlarged portion 30 of the bleed port 21 and of the inlet port 13 in combination with the relative distances from the fulcrum point of member 15 determine when the bleed port will pop open.

The present invention provides a relatively simple bleed or leak system for the compressor and load system while minimizing the power requirements and the capacitor specifications for the required air delivery and the losses.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. A fluid pump having a pumping chamber and an outlet chamber and having an inlet port member opening and closing a port from the pumping chamber to a fluid source and having a movable pump member in the pumping chamber with a suction stroke to move the port member to open the inlet port and draw fluid into the pumping chamber and a compression stroke to transfer the fluid through a valved outlet port of the outlet chamber, the improvement comprising a wall means separating said pumping chamber and said outlet chamber having a leak passageway joining said chambers, and

a valve means connected to the leak passageway responsive to the relative pressure in the pumping chamber and the outlet chamber to open said leak passageway during the suction stroke and close the passage-way during the compression stroke, and

means responsive to stopping of the movable pump member to simultaneously open the pumping chamber to a referenced pressure and the valve means.

2. In a fluid pump having a compression chamber and a high pressure outlet chamber and having an inlet port to the compression chamber and an inlet valve member responsive to the pressure of the compression chamber and having a member in the compression chamber having a suction stroke to move the valve member to open the inlet port and draw fluid into the compression chamber and a compression stroke to transfer the fluid into the outlet chamber, the improvement in said pump comprising a wall means separating said compression chamber and said high pressure outlet chamber and having a leak passageway, one end of the leak passageway terminating in the high pressure chamber and the opposite end terminating beneath the inlet valve member whereby said passageway is selectively and directly opened and closed by the movement of the inlet valve and means placing the inlet valve member to open the port and the leak passageway with the pump in a non-operating state.

3. The fluid pump of claim 2 wherein said wall means forms the outer wall of the compression chamber and includes the inlet port and said leak passageway, said valve member including a thin flexible metal plate secured at one end to the wall means and extending therefrom overlying the inlet port and the leak passageway.

4. The fluid pump of claim 2 wherein said leak passageway includes a small orifice portion extending from the high pressure chamber and an enlarged portion extending from the compression chamber.

5. A pressure relieving means for an air compressor and the load system, said compressor having a high pressure chamber and a compression chamber,

a chamber wall of the compression chamber having an inlet port formed therein,

a valve for said port including a relatively thin flexible plate overlying said port,

attachment means for securing an end portion of said plate to said chamber Wall with the other end portion of said plate engaging said wall and being movable from the Wall, said valve seat and chamber wall being so configurated that under normal atmospheric pressure the intermediate portion of said flexible plate is slightly spaced from said wall to render said inlet port partially open and relieving the compression chamber to open said valve with said plate spaced from the wall and port, and

a leak port having one end aligned with the free end of said flexible plate and closed with the plate engaging the wall and the opposite end terminating Within said high pressure chamber.

6. The pressure relieving means of claim 5 wherein said wall is common to both the high pressure chamber and the compression chamber and said inlet port is centrally located, and said leak port is located to the side of the input port diametrically opposite the attachment means.

7. The pressure relieving means of claim 5 wherein said leak port includes a reduced orifice portion spaced from the end of the flexible plate.

8. In an air compressor, comprising a compressor cylinder including an operating pistondiaphragm unit Within a cylinder and a head secured to the cylinder with a valve plate forming a common wall between a compression chamber and a high pressure discharge chamber formed within the head, said wall having a central inlet port,

a resiliently mounted valve member overlying said inlet port, said valve member including a portion being normally spaced from the inlet port to unload the cylinder when the compressor is not operating and another portion engaging the valve plate, and

said head including a leak port extending from the valve plate face forming a part of said high compression chamber and terminating in alignment with the valve member portion normally engaging the valve plate.

9. The air compressor of claim 8 wherein the leak port is substantially smaller than the inlet port and said leak port includes a reduced orifice portion spaced from the end aligned with the valve member.

10. The air compressor of claim 9 wherein said valve member is a spring metal plate secured at one end to the valve plate diametrically opposite from the leak port and extending therefrom with the outer free end overlying said leak port, said spring metal plate being crowned in alignment with the inlet port.

References Cited UNITED STATES PATENTS 1,495,491 5/1924 Le Cain 137493 2,193,244 3/1940 Wolcott. 2,198,722 4/ 1940 Horwath 103-41 2,213,248 9/1940 Jennings. 2,214,364 9/1940 Edwards 137493 2,249,326 7/1941 Rabe 10341 2,511,494 6/1950 Cohen. 2,520,674 8/ 1950 Buschmann. 2,536,995 1/ 1951 Hadley 23024 2,594,815 4/1952 Smith. 2,622,762 12/ 1952 Parsons 137--493 X 3,031,861 5/ 1962 McCormack. 3,043,404 7/1962 Peras 137493 X DONLEY J. STOCKING, Primary Examiner. W. L. FREEH, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,358,908 December 19, 1967 Norbert J. Gawin It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 35, for "compressor" read compressors column 5, line 15, for "of" read to Signed and sealed this 18th day of March 1969.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

1. A FLUID PUMP HAVING A PUMPING CHAMBER AND AN OUTLET CHAMBER AND HAVING AN INLET PORT MEMBER OPENING AND CLOSING A PORT FROM THE PUMPING CHAMBER TO A FLUID SOURCE AND HAVING A MOVABLE PUMP MEMBER INTHE PUMPING CHAMBER WITH A SUCTION STROKE TO MOVE THE PORT MEMBER TO OPEN THE INLET PORT AND DRAW FLUID INTO THE PUMPING CHAMBER AND A COMPRESSION STROKE TO TRANSFER THE FLUID THROUGH A VALVE OUTLET PORT OF THE OUTLET CHAMBER, THE IMPROVEMENT COMPRISING A WALL MEANS SEPARATING SAID PUMPING CHAMBER AND SAID OUTLET CHAMBER HAVING A PEAK PASSAGEWAY JOINING SAID CHAMBERS, AND A VALVE MEANS CONNECTED TO THE LEAK PASSAGEWAY RESPONSIVE TO THE RELATIVE PRESSURE IN THE PUMPING CHAMBER 